Methanolysis Process in PET Bottle Recycling

Chemical-biological integrated process for recycling polyethylene terephthalate (PET) plastics into high-value chemicals. The process involves using glycolysis with betaine catalyst to depolymerize PET into oligomers. This is followed by enzymatic hydrolysis to convert the oligomers into terephthalic acid and ethylene glycol. The bacteria strain E. coli is then used to convert the terephthalic acid into pipecarboxylic acid (PCA). Finally, Gluconobacter oxydans converts the ethylene glycol into glycolic acid (GLA). The entire process uses the reaction products as feedstock without purification, enabling a closed-loop, high-yield, and economical recycling of PET plastics into valuable chemicals.

Source

A process to efficiently convert polyester resins like PET into terephthalic acid derivatives like DMT using a catalyst called glycoxide. The process involves mixing the polyester with glycoxide, a solvent for swelling the polyester, and an alcoholic solvent. The glycoxide catalyzes the esterification reaction to form the desired terephthalate derivatives. The glycoxide can be made by heating ethylene glycol with sodium hydroxide.

Source

A process for recycling PET plastic waste into terephthalate ester monomers, like dimethyl terephthalate (DMT), without any pretreatment steps and in less than an hour. The process involves two stages: (1) depolymerization of PET by methanolysis using an alcohol like methanol and an ester catalyst like titanium ethoxide; (2) separating and purifying the DMT from the reaction mixture. The mild conditions and catalyst selection prevent isomerization or degradation reactions.

Source

A process to efficiently depolymerize polyethylene terephthalate (PET) into dimethyl terephthalate (DMT) and monoethylene glycol (MEG) using catalytic amounts of sodium methoxide. The process involves breaking down PET back into its starting materials by reacting it with methanol in the presence of sodium methoxide as a catalyst. The resulting DMT and MEG can then be separated and purified for use in various applications. The process allows for selective depolymerization of PET into its monomers in high yields and with low impurity levels.

Source

A process for recycling PET plastic waste into dimethyl terephthalate (DMT) monomer powder in a few hours by using mild reaction conditions. The process involves three stages: (1) pretreating the PET fragments to facilitate depolymerization, (2) reacting the pretreated fragments with methanol in the presence of catalytic amounts of bases like sodium methoxide, DBU, or potassium hydroxide, and (3) heating for 3-5 hours at 25-80°C. The mild conditions prevent isomerization or degradation of the DMT, allowing a complete reaction without the need for extensive purification.

Source

Recycling polyester waste into usable chemicals like dimethyl terephthalate (DMT) and cyclic carbonates by depolymerizing the polyester with methanol. The process involves depolymerizing the polyester in a reactor to form DMT and diol, then converting the diol into a form that won't react with DMT. This prevents DMT loss during further processing. The diol conversion step can be done in the same reactor as depolymerization. The diol conversion can be using compounds like cyclic carbonate precursors, allowing in-situ formation of cyclic carbonates. This avoids separating out DMT and diol for separate reactions.

Source

Catalysts for methanolysis of poly(ethylene terephthalate) (PET) to form dimethyl terephthalate (DMT) that provide improved performance compared to conventional catalysts like zinc acetate. The new catalysts, such as sodium carbonate, magnesium methoxide, 1,8-diazabicyclo[5.4.0]undec-7-ene, and triazabicyclodecene, allow methanolysis of PET at lower temperatures and with less methanol than zinc acetate. They also tolerate lower quality PET waste feeds.

Source

Catalysts for methanolysis of poly(ethylene terephthalate) (PET) that provide improved depolymerization efficiency compared to the traditional zinc acetate catalyst. The new catalysts include sodium carbonate, magnesium methoxide, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and triazabicyclodecene (TBD) which allow PET depolymerization at lower temperatures and with less methanol compared to zinc acetate. This reduces energy consumption and cost for recycling PET waste.

Source

Method for recycling waste polyester into new polyester using alcohol decomposition followed by transesterification. The method involves melting the waste polyester, adding ethylene glycol for pre-alcohol decomposition, then decomposing the melted polyester in an alcohol solvent with a catalyst. This step yields a transesterification product. Next, transesterification is performed in a separate kettle using the transesterification product, ethylene glycol, and catalyst to produce dimethyl terephthalate (DMT) and ethylene glycol. The purified DMT is recycled for polyester production.

Source

Efficient and economical process for recycling PET plastic waste into dimethyl terephthalate (DMT) and monoethylene glycol (MEG) for reuse in new PET production. The process involves depolymerizing PET using methanol and sodium methoxide at controlled ratios and temperatures. The key steps are: (i) adding sodium methoxide to PET waste, (ii) adding methanol in multiple fractions, (iii) heating to depolymerize, and (iv) separating DMT and MEG. This allows selective degradation of PET into the desired products with high yields. The optimized conditions are: 1:5-1:20 mol/mol sodium methoxide:PET, 0.2-3.0% mol/mol sodium methoxide in

Source

Efficiently converting polyester materials like PET into terephthalic acid using a simple, low-energy process. The conversion involves mixing the polyester with a suspension of monosodium glycolide. This allows selective hydrolysis of the polyester chains into terephthalic acid and glycols, which can be separated and recycled. The process is catalyzed by the glycolide suspension, avoiding the need for expensive catalysts like sodium methoxide.

Source

Producing bio-based polyethylene terephthalate (PET) from renewable sources like sugarcane, corn starch, fruit peels, agricultural waste, etc. The process involves converting these materials into intermediates like monoethylene glycol (MEG) and terephthalic acid (TA) which are then polymerized to form bio-based PET. This allows making biodegradable PET packaging and containers from renewable feedstocks instead of fossil fuels.

Source

A process for recycling polyester that involves depolymerizing the polyester using methanolysis, hydrogenating the resulting dimethyl terephthalate to cyclohexanedicarboxylate and cyclohexanedimethanol, and hydrogenating the side species like dimethyl phthalate, bisphenol A, and adipic acid diester. This converts undesirable side products into more valuable compounds that can be isolated. The hydrogenation and isolation steps improve the overall quality and commercial value of the recycled polyester stream.

Source

A method for depolymerizing polyesters using methanolysis that increases polyester depolymerization and reduces methanol requirements. The method involves treating the polyester with methanol in a reactor to form dimethyl terephthalate and diols. Some of the diols are then converted to non-reactive compounds like cyclic carbonates. This allows the diols to react further without interfering with the dimethyl terephthalate. The non-reactive compounds are separated from the dimethyl terephthalate to prevent further reactions. This prevents excessive methanol usage compared to traditional methanolysis where all diols react with methanol.

Source

Recycling polyester waste to produce useful chemicals while minimizing environmental impact. The method involves treating the product stream from polyester depolymerization by methanolysis to convert side species like dimethyl phthalate, dimethyl isophthalate, bisphenol-A, adipic acid diester, and colorants into valuable compounds. This is done by hydrogenating the side species along with the dimethyl terephthalate. The hydrogenated side species can then be isolated and further processed or disposed of more easily. This allows converting unwanted side products into valuable chemicals instead of disposing them, reducing waste.

Source

Continuous method for recycling waste polyester into dimethyl terephthalate (DMT) using alcohol decomposition and transesterification. The method involves drying and deoxygenating the waste polyester to prevent side reactions. The dried polyester, alcohol, and catalyst are continuously fed into a first alcohol decomposition reactor. The product is further decomposed in a second reactor. The alcohol-decomposed material is then subjected to transesterification with more alcohol and catalyst to yield crude DMT. Crystallization, separation, and purification completes the recycling process.

Source

Continuous process for recovering waste polyester like PET bottles and converting it into usable chemical feedstock like dimethyl terephthalate (DMT) for making new polyesters. The process involves two steps: continuous alcoholysis of waste polyester using ethylene glycol (EG) followed by continuous transesterification using methanol. The alcoholysis is done in two stages to remove excess EG. This allows high DMT yield and quality without distillation or concentration. The transesterification is done in two stages to improve conversion. The process starts with drying and deoxygenating the waste polyester to remove moisture and oxygen.

Source

A method for degrading waste polyester like polyethylene terephthalate (PET) into dimethyl terephthalate (DMT) with high efficiency and low equipment requirements. The method involves two-step alcoholysis using glycols followed by methanol transesterification. In the first step, preliminary alcoholysis at 150-190°C converts PET into a slurry with 20-60% depolymerization. This slurry is then subjected to deep alcoholysis/methanol transesterification at 190-200°C. The mixture of glycols and methanol promotes PET depolymerization and moves the alcoholysis equilibrium forward. This accelerates both steps and improves material utilization compared to separate alcoholysis and methanol transesterification.

Source

Efficient and cost-effective process for recycling polyethylene terephthalate (PET) into dimethyl terephthalate (DMT) and monoethylene glycol (MEG) using sequential addition of methanol and sodium methoxide. The process involves mixing PET with a first portion of methanol to swell the PET, followed by addition of sodium methoxide. Additional methanol is then added in fractions over time to depolymerize the PET into DMT and MEG. This sequential methanol addition helps control the reaction conditions and prevents excessive methanol consumption.

Source

Continuous alcoholysis recovery method for waste polyester that allows recycling of waste polyester materials like PET into dimethyl terephthalate (DMT) through chemical recycling. The method involves continuous alcoholysis of the waste polyester using ethylene glycol (EG) as the alcoholysis agent in a series of alcoholysis kettles. The alcoholysis is optimized by controlling the molar ratios of -COOH and -OH groups. This homogeneous molten-state alcoholysis with quantitative catalyst and EG ratios avoids solid-liquid heterogeneity and long reaction times. The alcoholysis product directly enters the transesterification tank without distillation or concentration steps. This continuous alcoholysis with optimized conditions enables stable product quality and saves equipment compared to batch alcoholysis.

Source